Wide-range high stability frequency generating system



Jan. 8, 1952 o. L.. MasoRLEY WIDE-RANGE H IGH STABILITY FREQUENCY GENERATING SYSTEM Filed Dec. `30. 1948 INVENTOR 0l mf MAC .SoRLEy ATTORNEY Patented Jan. 8, 1952 WIDE-RANGE HIGH STABILITY FREQUENCY l `GENERATING SYSTEM `Olin L. vltIacSorley, Collingswood, N. J., assigner to Radio Corporation of America, a corporation e of Delaware VApplicatiolrDeceemyber 30, 1948, Serial No. 68,263

l 'lhis invention relates to `an improvement on that disclosed by a `copending applicationof Harris A. Robinson, oser. No. 14,666, filed March 13, ,1948, which ripened into Patent #2,568,412 on September 18,1951. It involvesa frequency generating system operable in amultiplicityof discrete steps over a wide frequency range with a high degree of frequency stability for any chosen step and .providingmeans of automatically tuning said system to any discrete frequency step, and whichmay be used as part of an automatically tuned radio receiver and/or transmitter which is operable over a wide frequency range with a high degreeof stability in its various selected output circuits. s The present invention is like that of the aforesaid invention in that (l) the output of a controllable frequency generator is mixed with that of a selected constant frequency to `produce a difference frequency, (2) such difference frequency is applied to the input of a frequency discriminatorand` ,(3), the output of the frequency discriminator is utilized to tune theV controllable frequency' generator and its associated circuits to the various selected frequencies within the dif; ferent bands covered by the controllable frequency generator. It is distinguished by the fact that the difference frequency involved in the aforesaid invention is combined with a ,constantv frequency to produce a second difference frequency which is applied to one of the frequency discriminators and to the input of an adjustable division ratio frequency divider. In this case, the outputof the adjustable frequency divider is applied to a phase detector in which it is compared with a constant frequency, Vand variation in the output frequency of the adjustable divider is utilized to regulate each selected output frequency of the controllable frequency generator with a high degree of accuracy.`

The purpose of the invention is toeprovide an improved frequency generating system which is operable over a wide frequency range with crystal accuracy at any one of the selected operating frequencies, and which may be used as the frequency determining source in an automatically tuned radio receiver and/or transmitter.

The invention will be better understood from the following description considered in connection with the accompanying drawing and its scope is indicated by the appended claims.

The single figure of the drawing is Aa block diagram wherein (l) the blocks bear explanatory legends, (2) single lines are used to indicate the electrical connections between` the elements "si clanes..v (o1. 25o- 20) represented by the various blocks, and (3) broken lines are used to indicate the mechanical connections between the `various control elements and the parts which they control.

As indicated by the drawings, a controllable frequency generator I0 has its `output frequency regulated by means including a reactance tube I I and supplies its outputto a frequency doubler I2 and a mixer |3-` The controllable frequency generator may be of any suitable type. For example, it may consist of a plate tuned feedback oscillator, such` asis often'fused in the art, having a number of tank coils, each with its associated feed back coil, `together with control switches for selecting any o ne pair of coils, and a variable condenser for varying the resonant frequency of the chosen tank coil over each band.

In the present. invention, these control switches of a generator` I0 are operated by means of a control knobV I4 which also functions to operate the band selection switches of a radio fre- .i

quency amplifier I5,` the converter 2|,and a harmonic selector circuit I'I for the harmonic generator I6.

The radio frequency amplifier I5 has its input connected through a switch I8 to a receiving antenna I9 and delivers its output through a switch 20 to a converter 2|. The converter 2| is also energized from the generator I0 through the frequency doublerl I2. The intermediate frequency output of the converter 2| is fed to an intermediate frequency amplifier 22 and thence to a detector and audio frequency amplifier 23.

The mixer I3 receives input from the generator I0 and from a constant frequency source 24 through the harmonic generator I 6 and the harmonic selector I'I.

The difference frequency output of themixer I3 is supplied touadifferent frequency selector jcircuit 25 and thence to 'a mixer 26. A frequency discriminator 21 also operates from the AVresonant circuit. of the frequency selector 25. s `The mixer 26 also receives a constant frequency 'input from a frequency divider 28 through a harmonic generator 29 and a harmonic selector 30.

The difference frequency output of the mixer 26 is applied to a difference frequency selector circuit 3|, the output ofwhich goes to an adjustable division ratio frequency divider 33. A

frequency discriminator 32 also operates from the resonant circuit of the frequency selector 3|.

The frequency discriminators may be of any suitable type such as those disclosed inthe aforesaid Robinson application. They function to control a tuning motor'34 which operates to tune the and 3E.

3 `radio frequency amplifier' I5, the converter 2 I, the frequency doubler I 2 and the controllable frequency generator I9 to the selected operating frequencies within the different bands selected by the control knob I4. A harmonic selector 30 is operated by a control 35, and the difference frequency seq lector circuit 25 is adjusted by both selectors 35 The difference selector circuit 3l and adjustable divider 33 are both controlled by selectors 36 and 31. 31 may be calibrated to read=directly the frequency of the receiver and transmitter.,"Inthis', u

case, the selector I4 will read thousands, the selector 35 hundreds, the selector36 tensl andthe selector 31 units. If desire'cLby proper'choiceof ratios in the variable divider, fractional kilocycles may also be obtained-Landeshownon: con@ trol 31. Also, for other applications, the controls can indicate the oscillator frequency directly.

summarizing: Controllhl operates the rst harmonic selector I1 and selects" the bandsforthe R. F. amplifier -I 5, the converter 2I, theffrequency doubler I-2,and the controlled ffrequency'generator IIJ. Control 35 operates-the second harmonic selector-Sfand partly tunes the iirstdifference selector 25.` Control v315completes-the tuning "of the first difference selector 2'5, partly tunes the second difference selector 3|, and setsthe 'tens section of theY variable ratio frequency divider 33'.- Control YV31 completes 4the tuning of the second diierence selector `circuit 3| and sets the units sectionA of the'variable'radio'frequency divider 33. The variable yratio Y'divider may be of the type described in `my copending application, Serial No. V16,8351, iiledMarch 24, 1948,'now Patent No. 2,560,968, issuedJuly 17, 1951.

A-phase detector-38 receives Yinputfrom the adjustable frequency-divisionratio divider -33 and a lputfrequency of 'the'controll'able' frequency generator I9 isY accurately regulated at any one'of its selectable values; Y

The selectors Ill, 35, 35 andA its two inputs, and functions to apply to the reactance tube I I a potential such that the output frequency of the generator I is maintained at the exact desired multiple of the output of the fixed ratio divider. Any deviation therefrom will cause achange in the relative phases, which will change the 1 outputof l:thefphase ttlisc'riminator `138, which will changethe control 'voltage'on the reactance tube II and'correct the frequency of the cont'rolled frequency generator I0.

IfrequencyJainplifierjiI 5 may be like that described "in Patent)"'2`g4l19,593.'

Y When 4the apparatus is utilized as a receiver, therswitc'hes.twiand20 are in their illustrated closed .positions and the operation is as indicated above. For operation as a transmitter, the switches I8 and 2D are nioved to their other closed positions=-fthus connecting `G12) the 'output of the amplifier-I 5-ito1the' input-of the transmitteramplifiers ('notshowii) ,andj (2l-tlf1e"inpu`t` df-'the ampli-Vv er-=l5- to "a `transmitter mixer 0 Lfrom whichfi's derived` an`v` output 1frequency dependentL 5 on the frequencyo'f'f the-'controllable 'frequencygeneratorr I'Ilandthatfof a crystal-- controlled generator il.

Assume fthe i following valuesv inthe receiver shownrfR. 'Fr 25.0 `:to 2399'9 megacyclesfI. 'Fr-1800 kc., constant frequency source-`5001kcqoperation every kilocycle. wouldireslt. 1

constant ireq.-generator 24 500 1re. Y f Harmonic selector 17 output 3. 3.5,4.0,.4.5,. ...13.0, 13.5 mc.

Fixed divider 28, ratio Harmonicsselector 30 output 700,'` 750,1'800,i A1100,.11'50kc. Flxeddivider 39,1atio 100 Fixed divider output'. 500 cycles' Controllblefreqfgenerator vl90(11lrc.-l l2;899.5'kc. Dilerence selector output.. 1100 to .600.5 kc.

Difference selector 31 output.-. 50 tov 99:5 kc.

00111555510015155533,ranio'rangel `100 1:0199 Adlustable divider 33 output.- 500 cycles K "SeeIflablefforfrequencies'aridl control settings fora 'groupoftypical operating'*frequencies.

Table 1 Block--- 15 12 1o 17 25 v.'10 1 -31 33V 14 35 fr 35 1:37J

0105.--. Rr 2115 Fc 151515110510l D10 Harmonie 'Dies' "Digign 'Thousads vfrenare-' 15- Tens-Units 2,000 3,800 1,900.0 3,000 1,100.0 1,150; 50.0' v 1'00 2 0 01. 0 2,020 3,820v A1,910.0 3,000 1,090.0 1,1501 y00.0- 120. .2" 0 2E 0 2,040 3,840 1,920.0 3,000 1,080.0 1,150..z 70.0; 140 j v2n 01 -'4, 0;: 2,090 3,890 1,945.0 3,000,` 1,055.0 1,150'r 95.0 V190 2 0 .9` 0 2,091- 3,891 1,9455 V3,000 1,054.5 1,4150 195.15V 191- A2 0 A `9 1 2,002 3,892 1, 940.0 3,000 11,054.0 1,150, l 90.0 v 102; 2y 0 9, -2 2,098 3,895, 1,949.0, 3,000 1,051.0 1,150 ,99.0 19sY 2 0 `.9', s 2,099 3,899 1,049.5c Y 3,000 1,050.5 1,150 f 199.5 109 2` -0 9v 0" 2,100 3,900 1,950.0 3,000 1,050.0 1,100 .50.0 y2 1 0` 0 2,101 3,901` 1,950.5 3,000, 1,049.5 1,100 50.5" 101 2 1.' 0' 1 I 2,200v 4,000l 2,000.10 3,000 1,000.0 '1,0501 50.01: '100- 2V` '2 Y 0v '0 2,900 4,700- 2,350.0 3,000 550.0 700- 50.11; 100; Y 2 .0. 0'Y v0: 2,990 4,790 2,395.0 3,000 005.0 700 05.0 2 0H 9 0 2,999 4,799 2,399.5 3,000 500.5 700 99.5 199' 2f l I9 9 9 i 3,1000` 4,800 2,400.0 3,500 1,100.0 1,150 50.0, .100 2E 0 .02 0 3,001 4,801 2,400.5 3,500 1,009.5 1,150 "50.5 101" j 3 0"V 50 1 3,999 5,799 Y 2,899.5 3,500 "000.5 4700VVV 99. Y 199 5 43 9- '91 *9 4,000 5,800 2,900.0 4,000 1,100.0 1,150 l .50 100- 4: A0-y .0fv -0 23,990 25,790 12,895.0 13,500 005.0 '700 95; 190. 23 9Y 9, 0 23,995 25,795 12,397.51 13,500 002.5 .7001 V97.1 1951 23-4 191 -9V 5 23,909v 25,799 12,809.5 13,500 000.5` .700 `90. .109 23 01 9 49,

Receiver, 2.0 to 23.999 me. inlOOO-cyeles steps.

Controlled osc. 1.9'to12.89995 n10. in 500 cycles steps. I. 11,1800 ke. First harmonic sclector,.3.0, 3.5, 44.0, 4.5, 12.5, 13.0, l3.5mc. l Second harmonic selector, 700, 750, 800, 850

iThe phase detector 38 may be vof any suitable type, such as thatdescribed in the copendingapplication of John D. Woodward, Serial No. 743,234, led April `23, 1947, now Patent VNo.V 2,490,499,'issuedDecember 20, 1949. It responds The control- .knob I4 will be operable 'to 222 diferentpositions and. will `function-m` Y r(.71) To tune vthe' harmonicselector `I1 'over a frequency .range ot 3to 13.5 mc. -in steps -of .0.5 mc., .and

to slight variations in the comparative phases of "f5 1(2)' "Io set the bands for the frequency doubler From this, the following v'alues- Z, the controlled freq. generator I0, and the R.`F. amp. I5. U-

Under these conditions, there is supplied to the input of the difference frequency selector 25 frequencies which range from 600.5 kc. `to 1100.0 kc. by steps of 0.5 kc. Such difference frequencies are supplied to the mixer 26. The resonant circuit of the difference selector 25 is arranged for decade tuning in the same manner as that used for the oscillator described and claimed in my copending application, Serial No. 743,266, filed April 23, 1947, Patent No. 2,532,455 granted December 5, 1950. Thus, the control 35 shifts the resonant frequency in steps of 50 kc. while the control 3B shifts the frequency in steps of 5.0 kc., and the two controls together provide 100 steps of 5.0 kc. each. p

In the mixer 26 these Ifirst differencefrequencies are mixed with the output of the harmonic selector 3U. Assuming the divider 28 to have a division ratio of 1 to 10, the input frequency of the harmonic generator 29 is 50 kc. and the control knob 35 is operable to ten different positions for selecting frequencies over a range of 1150 to '700 kc. by steps of 50 kc.

The difference frequency output of the mixer 26 is supplied to the difference frequency selector V3| which is` tuned by the control knobs 36 and 31 over a frequency rangeof 50 to 99.5 kc.

by one hundred equal steps, control 36 giving ten steps of 5.0 kc. each and control 31 dividing each step into tentparts of 500 cycles each. These differencefrequencies are supplied to the input of the adjustable division ratio frequency divider 33.

The tens selector knob 36 and the units selectorA knob 31 function to select the frequency division ratio of the divider 33 so that the output frequency of this divider is very nearly the same as that of the fixed frequency divider 39, being exactly the same when control is established. Underthese conditions, the phase detector 38 functions to apply to the reactancetube I l a potential which is responsive to relative variations in the phase of the outputs of dividers 33 and 39, which is utilized to stabilize the output frequency of the generator I at each of its selected values.

What is claimed is:

l. In a wide range radio receiver wherein the outputs of a radio frequency amplifier and a controllable frequency Wave generator are mixed to produce the input to an intermediate frequency amplifier, said receiver including a first mixer circuit wherein the output of said generator is mixed with harmonics of a first constant frequency wave to produce a first series of selected difference frequency Waves, the combination of rst selector means coupled to said first mixer circuit for selecting one difference frequency Wave from said first series of different frequency waves, `circuit means to which said first constant frequency wave is applied to producea second constant frequency wave, means coupled to said circuit means for selecting harmonies ofsaid second constant frequency wave.

v fa second mixer circuit for mixing said harmonics of Vsaid second constant frequency with said first `series of difference frequency waves to produce a second series of difference frequency waves,

`second selector means coupledto said second mixer circuit for selecting one Wave from said second series of difference frequency waves, means including a pair of frequency discriminators individually coupled tosaid first and said second selector means and responsive respectively to said first and to said second series of difference frequency waves and means responsive to the relative outputs of said discriminators for tuning said controllable frequency generator and said radio frequency amplifier, and means including an adjustable division ratio frequency divider coupled to said second selector means and responsive to said second series of difference frequency waves for stabilizing the output wave of said controllable frequency generator at each of its selected operating frequenc1es.`

` 2. In a wide range radio receiver wherein the outputs of a radio frequency amplifier and a controllable frequency wave generator are mixed Yto produce the` input to an intermediate frefrequency wave and to tune said radio frequency amplifier and said controllable frequency generator to a predetermined frequency band, means l for selecting one difference frequency wave of said first series of difference frequency waves, means for selecting a harmonic of a second constant frequency wave, means for mixing said first selected difference frequency wave with said selected harmonic of said second constant frequency wave toproduce a second difference frequency wave, means including a pair of frequency discriminators responsive respectively to said first and to said second selected difference frequency waves for tuning said controllable frequency generator and said radio frequency amplifier roughly to an operating frequency within said band, and means including an adjustable division ratio frequency divider responsive to said second selected difference frequency wave for stabilizing the output wave of said control- `lable frequency generator at said selected operating frequency.

3. In a wide range controllable frequency wave generator wherein the output wave of said generator is mixed with a harmonic selected from a first group of harmonics of a constant frequency wave source to produce a first series of difference frequency waves, the combination of unitary control means operable to select one of said harmonics of said 'first constant frequency and to tune said controllable frequency generator to a predetermined frequency band, means for selecting a difference frequency Wave from said first series of difference frequency waves, means for selecting a harmonic of a second constant frequency wave, means for mixing said first selected difference frequency wave with said selected harmonic of said second constant frequency to produce a second difference frequency Wave, and means including an adjustable ratio frequency divider responsive to said second difference frequency wave for stabilizing the out- 27 f- .rputzewaveiof fsaidc.v controllable:frequencysgenera- 'sztor ate. am .operating-s frequency.

In. a wideirange* .controllable .frequency-wave .eneratore.whereinI .the 1 output waivelofrsaidfigenserator; is-mixed .in aA mixinggcircuit: .with .afhari-.zrnonic 1 selected from a firstl group. ofiharmonics .1 -:of a constant frequency Waveisource: to .-:produce aifrst .series f. of f. yselected L.: difference z' frequency l '.--Wavesr the. comlcinationA ofxunitary..l control means K operableito: select agharmonic ofsaidrstiaconstan-.tz frequency: wave; and; to-.itune .said controlfiable: frequency; generator '.to-v4 a predetermined 4:frequency loand;` :first1 selector'fmeansifor.. select- .ing a' differencerfrenquency- -wave i from.said;rst series Tof f Hdifere-ncerp' frequency fawaves, Lcircuit LAmieans coupled to. said i constantV frequency wave :source Eto produce` a second:v constant'.- frequency ave; .harmonic selecting#meansgcoupled .to said f1. circuit-@means for selectingV afazharmoniciiofi said .esecond'constant frequency Wave, a secondfmixing. 4circuit coupledto Ysaid iirst: selector means and said harmonic selecting means for mixing said 1 rstf series fof.v difference :frequency Waves.. with said selectedharmonic Vof said: second.` .constant frequencysto fproduce a 'second seriesf.l ofldiffergencer frequency waves, '..second V selector. fmeans 2 'cou-pled to said second mixingv circuit. *forfselecteinglone wave from said zsecond; seriesof differf encegfrequencyr Waves,b means including a pair of-.f-frequencyf: discriminators individually. coupled lto :thesaid .rst-.and-.said secondselector means and-responsive respectively/to said. rstfandto said-secondfseries off difference frequency waves for tuningsid.controllable frequency wave genl -erator to equally.' spaced V.frequencies within said ',yband, and .ffmeansincluding .ian 'adjustable di- '.vision ratio frequency .divider `coupled to. -said secondselector meanstandiresponsiveto said second series of difference:frequency-waves =for ..-.fstabi1izi ng thel .output frequency-s vWave ofl said- ...-contrcllable frequency -wave generator atieach .of .its-'selected Y operating.; frequencies.

Sit-Afwide range, frequency-.stablefwave gen- .erating circuit.arrangementincluding a control- ....lab1efrequency .Wave generator, a constant. fre-wV .-quency vwave generator, a-:mixer vcircuitg-,ccnnec- .tions coupling the outputs-.cfaV said". vcontrollable H'frequencyfand said .constant frequency .wavegenerators to-said-mixer. to `produce azdifference'fre- 1 quencywave, Y -a zdiierencefrequency. 'iwaveselector circuit coupled; tosaidi; mixer to. receive v`said dierencerfrequency Wave., aisecondv mixer cirncuit; further connections' coupling: the outputs Lof said difference frequency wave-fiselectorfcircuit and-..saidfconstant, frequency:wave.lv generator tosaid fsecond mixer vto produce; a secondi; diff-'erencei frequency.. wave; a second' differencehfreiquencyfwave .selector circuitcoupled. to said; sec- .0nd mixer toreceivesaid second .difference frequency wave, an.: adjustable ratioffrequency-di-"v:

a', .erating circuitarrangement including. acontrol-" .diagrammi .lablezzfrequency. wave generator; a constant-. frequency Wave generator, a mixercircuitpconnec- --tions-r-couplingthe outputs. of said. .controllable `frequency and-said constant frequency 'Wave gen- 5` erators to saidmixer vtoproduce a Vdifference frequency Wave,..a harmonic frequency Wave'wgenn erator fand-al harmonic frequency wave selector circuitI interposed; :between said constant; fre- -quency wave"-generatorf'andsaid mixer circuit, a

1edifference-'frequency Wave vselector circuit Ycoupled toasaid;.mixertoareceivesaid differencegire- 1 quency 1.. wave', awssecondz :mixer circuit, further connections*.couplingV the..o.utp.uts:ofJsaid-diference frequency. .waveaselecton .circuiti and said constant :frequencyewave generator tozrsaid;` secvond @mixern touproducev azisecondf difference.: fre- Mquency wave, a'.lxed :ratio`v frequency :divider f circuit, a r further 2 -liarmonic f frequency Wave 1 generator and a further harmonic frequency wave fselector circuit interposed` betweenasaid constant -.v.. frequency Wavegenerator and said-secondmixer circuit, a -secondl difference.rfrequencyiwave selector circuit coupled tVo-'saidI-second mixer, aan Vadjustable -ratiosfrequency divider circuit.- coupled to said second differencefrequency-Wave VVselector"'circuit afl-phase'-fdetectorV circuit, additional l connections coupling the outputs 'of said adjustablev ratio frequency-divider circuit and said/constant 'frequency wave generator Ato said fic-phase detector to produce .afpotentia'l `vproportional-to the phase fdifference'- between the fwave fof' :said second mixer and-said' constant frequency wave output, -ai-secondflxed `ratio frequency difrequencyA Wavelfgeneratorl and-said phase detecs vtorV circuit,A and a-'reactanc`e ltube circuit having an input coupled-tofsaidtphaseJ-detectorfcircuit 1f andl :am output coupled' Lto-said: controllable frequency Wave generator. i0 i `*7. Aswidefrange, frequency-stable.;wave-igens..zferatingcircuitsarrangement including a control- `:.zlaolei` frequency. :.w-ave generator,` ai constant frequency wave generator, a mixer circuitrconnecltionsacouplingrithef` outputs :gofcsaido: controllable 4 .3 l frequency'and-said constantfrequency -wave .gen-

. -1 craters -j to: saidx-zmixereto produce at dierence frequency. wave; a v,difference frequency wave jsef.lector-circuit..coupled.to fsaidz: mixer to receive -..said difference frequency-wave, af-second mixer v. circuit...further connectionsiincluding a xedra- ...-tio frequency-dividercircuit couplingzthe outputs of .said -diii'erence frequencs7- 4Waver-:selector .cir-

.cuit-.and saidfconstant .frequency wave generator Y to saidjsecn'd.Vmixerito..produce a second difference.` frequency.v Wave, a, second .difference Afrequency wave selector circuit coupled., to said second mixer circuit to select.said. seconddiffer- .ence frequency Wave, first .and second frequency f-discriminator circuits coupled` to said rst and s'eccnddifferencefrequency selector circuits re- A vspectively; Land a "tuningfcontrol circuit coupled `tc saidconti'ollable frequency generator totune f 1 theesaine*broadlyd in'response to the 'relative outeputsiof Vsaid frequency' -`discrirninatorl circuits,"an

1.-.65fadiustableuratio; frequency* divider'circuit couv fpled tcs'aid second ldiference' frequency selector ff circuit, a-l-phase detector circuit;V a second Yfixed f ratio-i frequency 1 divider; vcircuit` connectedto` said `vfii-xed"ratio :frequency Vdivider circuit; additional 7o .connections couplingV the# outputs of said second .vadi-fference frequency selectorfand Vsaid 'fixed raretio frequency divider circuitsto Ysaid-phaseiievtectorzto; produce .afpotential `proportional to V:the `,phasefdiffcrence betweenftheoutput Wavestherevider` circuit interposed between f 4said constant 9 coupled to said phase detector circuit and an output coupled to said controllable frequency generator to tune the same exactly to said operating frequency.

8. A wide range, frequency-stable wave generating circuit arrangement including a controllable frequency wave generator, a constant frequency wave generator, a mixer circuit, connections coupling the outputs of said controllable frequency andsaid constant frequency wave generators to said mixer to produce a difference frequency wave, a harmonic frequency wave generator and a harmonic frequency wave selector circuit interposed between said constant frequency wave generator and said mixer circuit, a difference frequency wave selector circuit coupled to said mixer to receive said difference frequency wave, a second mixer circuit, further connections coupling the outputs of said difference frequency wave selector circuit and said constant frequency wave generator to said second mixer to produce a second difference frequency wave, a fixed ratio frequency divider circuit, a further harmonic frequency wave generator and a further harmonic frequency wave selector circuit interposed between said constant frequency wave generator and said second mixer circuit, a second fixed ratio frequency divider circuit, a second difference frequency wave selector circuit coupled to said second mixer circuit to select said second difference frequency wave, rst and second frequency discriminator circuits coupled to said first and second difference frequency selector circuits respectively, a tuning control circuit coupled to said controllable frequency generator to tune the same broadly in response to the relatively outputs of said frequency discriminator circuits, an adjustable ratio frequency divider circuit coupled to said second difference frequency selector circuit, a phase detector circuit, additional connections coupling the outputs of said second difference frequency selector and said fixed ratio frequency divider circuits to said phase detector to produce a potential proportional to the phase difference between the output waves thereof, and a reactance tube circuit having an input coupled to said phase detector circuit and an output coupled to said controllable frequency generator to tune the same exactly to said operating frequency.

9. A wide range, frequency-stable wave gen- 10 erating circuit arrangement including a controllable frequency wave generator, a constant frequency wave generator, a mixer circuit, connections coupling the outputs of said controllable frequency and said constant frequency wave generators to said mixer to produce a difference frequency wave, a harmonic multiplier circuit interposed between said constant frequency Wave generator and said mixer circuit, a difference frequency wave selector circuit coupled to said mixer to receive said difference frequency wave, a second mixer circuit, further connections coupling the outputs of said difference frequency wave selector circuit and said constant frequency wave generator to said second mixer to produce a second difference frequency wave, a further harmonic multiplier circuit interposed in said further connections, a second difference frequency wave selector circuit coupled to said second mixer to receive said second difference frequency wave, an adjustable ratio frequency divider circuit coupled to said second difference frequency wave selector circuit, a phase detector circuit, additional connections coupling the outputs of said adjustable ratio frequency divider circuit and said constant frequency wave generator to said phase detector to produce a potential proportional to the phase difference between the wave output of said second mixer and said constant frequency wave output, an additional frequency divider circuit interposed between said constant frequency wave generator and said phase detector, a reactance tube circuit having an input coupled to said phase detector circuit and an output coupled to said controllable frequency wave generator.

OLIN L. MACSORLEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

